Attenuation of the dorsal root ganglion response to 5-HT by Mn2+. Sucrose gap recordings from the dorsal root of the DRG. In No. 1, the 5-HT and GABA responses, recorded in a normal superfusate, are shown in the left- and right-hand columns, respectively. The superfusate composition was then switched so as to contain 2 mM MnCl2. After 2.5 hr exposure, the 5-HT and GABA responses were again determined as shown in No. 2. Note the slow after-hyperpolarizing phase of the 5-HT response which is accentuated here by slowing the time base. Recovery of the 5-HT response is shown in No. 3, 45 min after return to the original solution containing no MnCl2. At the indicated points 1 mM 5-HT and 1 mM GABA were bath applied.